During an 11-year study ending in 2010, Spanish researchers estimated the fatty acid intake of over 12,000 university graduates to evaluate the association between fatty acid intake and depression.
The fatty acids included saturated, polyunsaturated, trans unsaturated, and monounsaturated fatty acids. They also recorded culinary fatty acids, such as olive oil, seed oils, butter, and margarine.
Following up with participants in later years (6 years later, on average), researchers classified them as having depression or not. They found that 657 participants had depression.
What researchers discovered was that there was a significant relationship between trans unsaturated fatty acid intake and depression risk, while there was only a significant association between the other unsaturated oils and not having depression. Results indicated an association between butter and an increased risk of depression, but they also indicated an association between olive oil and a decreased risk.
Fish oils (like omega 3 and omega 6), seed oils, and margarine, seemed to have no significant impact on depression risk; they neither increased nor decreased one’s risk of being depressed.
Researchers concluded that their study suggested “that cardiovascular disease and depression may share some common nutritional determinants related to subtypes of fat intake.”